考虑注浆圈与复合衬砌时体外排水方式设计

Design of External Drainage Mode Considering Grouting Circle and Composite Lining

基于反映法、叠加原理及渗流力学理论构建了是否含注浆圈的两种体外排水简化计算模型,推导了隧道与体外排水洞涌水量的计算公式、隧道二次衬砌外水压力表达式,通过解析退化验证了理论模型及解析公式的正确性与适用性,根据推导公式进行了参数敏感性分析,最后通过数值模拟进一步进行了检验.结果表明:体外排水洞与隧道涌水量均随注浆圈渗透系数的下降而非线性降低,隧道二次衬砌外水压力随注浆圈渗透系数的下降而非线性增大,但其临界值小于常规排水方式;增加初期支护的厚度可达到降低二次衬砌外水压力及隧道涌水量的目的;围岩与注浆圈、注浆圈与初期支护渗透系数合理比值分别为15与100,同时须严格控制二次衬砌渗透系数;排水洞洞径对体外排水洞涌水量影响显著,为保护地下水资源,体外排水洞洞径推荐为0.2 m.

Based on the reflection method,superposition principle and the theory of seepage mechanics,two sim⁃plified calculation models for external drainage with or without grouting ring are constructed.The calculation formu⁃las for the inflow of the tunnel and the external drainage tunnel,and the external water pressure expression of the sec⁃ondary lining of the tunnel are deduced.Analytical degradation verifies the correctness and applicability of the theo⁃retical model and analytical formula.The parameter sensitivity analysis is carried out according to the deduced for⁃mula,and finally it is further tested through numerical simulation.The results show that the water inflow of the exter⁃nal drainage tunnel and the tunnel decreases nonlinearly with the decrease of the permeability coefficient of the grouting circle,and the external water pressure of the secondary lining of the tunnel increases nonlinearly with the de⁃crease of the permeability coefficient of the grouting circle,but the critical value is less than conventional drainage method;increasing the thickness of the initial support can achieve the purpose of reducing the external water pres⁃sure of the secondary lining and the amount of water inflow of the tunnel;the reasonable ratio of the permeability coef⁃ficient for the surrounding rock to the grouting circle,as well as the grouting circle to the initial support,is 15 and 100,respectively,and at the same time,the permeability coefficient of the secondary lining must be strictly con⁃trolled;the diameter of the drainage tunnel has a significant impact on the inflow of the external drainage tunnel.To protect the ground water resources,the external drainage tunnel diameter is recommended to be 0.2 m.